Subacute superior patellar pole sleeve fracture.

Patellar fractures are uncommon, representing 1% of pediatric fractures. Most of these injuries are sleeve avulsions of the inferior pole. Sleeve avulsion of the superior pole is rare, with only 14 cases reported in the English-language literature. These injuries occur in adolescents after forced knee flexion or direct anterior blow. Radiographs may reveal patella baja, anterior tilt, and suprapatellar calcifications. Ultrasound and magnetic resonance imaging (MRI) can confirm the diagnosis. We present a subacute superior pole sleeve fracture in a 15-year-old boy who sustained a left knee injury. Initial radiographs were negative. Ten days later, the patient returned with hemarthrosis and suprapatellar calcification. MRIs were read as "distal quadriceps tendon tear." Twenty-three days after the injury, the patient presented with a limp, palpable quadriceps tendon gap, and inability to maintain a straight leg raise. A superior pole sleeve fracture was repaired surgically the following day. An understanding of the injury demographics and radiological findings associated with superior pole sleeve fractures can prevent missed diagnosis of a rare injury. We review the literature for injury demographics, operative and nonoperative treatment methods, and outcomes.